The present invention relates to the field of electronics, and in particular, to a control device for a vehicle engine.
Engines of modern vehicles, such as automobiles, for example, have various electronic systems which enable their operation to be controlled in the best possible manner. These systems are controlled by a device which sends corresponding control signals to the engine in accordance with configuration parameters stored in a non-volatile memory of the control device. The memory is typically a flash EEPROM.
During an operation to calibrate the control device, the configuration parameters are corrected to modify operation of the engine. This calibration operation is typically performed in the factory at the vehicle development stage or in the workshop, to adapt operation of the engine to various environmental conditions or to the deterioration of the components.
The calibration operation is generally performed in the field while the engine is in operation in order to check directly the results of the modifications applied. For this purpose, the control device is connected to an external computer which controls the modification of the configuration parameters read from the flash memory of the control device. However, the configuration parameters cannot be modified in real time directly in the flash memory of the control device. The writing operation in fact involves the need to cancel the contents of the flash memory at least in blocks, and the configuration parameters are therefore not available at the same time for controlling operation of the engine.
A known approach includes using a specially constructed or custom interface card which is connected to the control device by a high-speed parallel bus. The external computer is then connected to the interface card by a standard connector. During the calibration operation, at least some of the memory space of the control device associated with the configuration parameters is re-mapped in a working memory (RAM) of the interface card. The configuration parameters can thus be modified directly by the external computer by a standard connection while, at the same time, being used by the control device. Upon completion of the calibration operation, the new configuration parameters are then downloaded from the RAM memory of the interface card into the flash memory of the control device.
However, this approach is very expensive because of the low production volumes of the configuration cards, and of the need to increase the number of external connection terminals of the control device to permit real-time access to the configuration parameters downloaded to the RAM of the interface card. In particular, in applications with high operating frequencies, the external connection between the control device and the RAM of the interface card slows down access to the configuration parameters so that the control device cannot be calibrated in the field with performance identical to its actual performance.
In view of the foregoing background, an object of the present invention is to prevent the above mentioned problems.
This and other objects, advantages and features according to the present invention are provided by a control device for a vehicle engine comprising a memory unit for storing engine configuration parameters, a processing unit for sending control signals to the engine in accordance with the configuration parameters, and an input/output unit connectible to an external computer to modify the configuration parameters.
The control device may further include a first portion and a second portion of the memory unit, with each portion being alternately used in an active state for storing a current version of the configuration parameters, or in an inactive state for the writing of a new version of the configuration parameters. The processing unit may access the portion which is in the active state for reading, and the input/out unit may access the portion which is in the inactive state for writing. Means are provided for selectively switching one of the portions to the active state and the other of the portions to the inactive state.
Moreover, the invention is also directed to a vehicle comprising the control device and a corresponding control method.